21764465 has 4 divisors (see below), whose sum is σ = 26117364. Its totient is φ = 17411568.

The previous prime is 21764459. The next prime is 21764467. The reversal of 21764465 is 56446712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3041536 + 18722929 = 1744^2 + 4327^2 .

It is a cyclic number.

It is not a de Polignac number, because 21764465 - 2⁶ = 21764401 is a prime.

It is a super-3 number, since 3×21764465³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21764467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2176442 + ... + 2176451.

It is an arithmetic number, because the mean of its divisors is an integer number (6529341).

Almost surely, 2^21764465 is an apocalyptic number.

It is an amenable number.

21764465 is a deficient number, since it is larger than the sum of its proper divisors (4352899).

21764465 is an equidigital number, since it uses as much as digits as its factorization.

21764465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4352898.

The product of its digits is 40320, while the sum is 35.

The square root of 21764465 is about 4665.2400795672. The cubic root of 21764465 is about 279.2003759201.

The spelling of 21764465 in words is "twenty-one million, seven hundred sixty-four thousand, four hundred sixty-five".